1. Field of the Invention
The present invention generally relates to light emitting diode (“LED”) arrays. The present invention specifically relates to a LED array powered by an alternating current supplied by a high frequency inverter circuit, and LED arrays controlled by impedance array that may be switching to accomplish dimming and switching functions.
2. Description of the Related Art
LEDs are semiconductor devices that produce light when a current is supplied to them. LEDs are intrinsically DC devices that only pass current in one polarity and historically have been driven by DC voltage sources using resistors to limit current through them. Some controllers operate devices in a current control mode that is compact, more efficient than the resistor control mode, and offers “linear” light output control via pulse width modulation. However, this approach only operates one array at a time and can be complex.
LEDs can be operated from an AC source if they are connected in an “anti-parallel” configuration as shown by patents WO98/02020 and JP11/330561. Such operation allows for a simple method of controlling LED arrays but which operate from a low frequency AC line. However, this approach employs large components and no provision is given for controlling the light output.
The present invention addresses the problems with the prior art.